EXPRESS: Effect of Dexmedetomidine on Postoperative Cognitive Dysfunction in Elderly Patients Undergoing Abdominal Surgery: A Systematic Review with Meta-Analysis

OBJECTIVE: To systematically evaluate whether perioperative intravenous dexmedetomidine (DEX) reduces postoperative cognitive dysfunction (POCD) in elderly patients undergoing abdominal surgery. METHODS: A systematic review and meta-analysis of randomized controlled trials (RCTs) was performed using PubMed, Embase, Cochrane CENTRAL, and Web of Science from database inception to 15 April 2026. Eligible studies included patients aged ≥60 years undergoing abdominal surgery under general anesthesia and compared intraoperative DEX with placebo. The primary outcome was POCD incidence assessed by the Mini-Mental State Examination (MMSE) or Montreal Cognitive Assessment (MoCA). Secondary outcomes included MMSE scores, tumor necrosis factor-α (TNF-α), and visual analogue scale (VAS) pain scores; interleukin-6 (IL-6) was summarized narratively because only two trials reported it. Risk of bias was assessed with the Cochrane Risk of Bias 1 tool. Random-effects models with Hartung-Knapp-Sidik-Jonkman confidence intervals were used irrespective of heterogeneity, and reporting followed the Framework for Approaches and Methods in Evidence Synthesis (FRAMES). TNF-α concentrations were significantly lower with DEX (MD=-38.70 pg/mL, 95% CI: -76.44 to -0.96; P=0.047), but the very wide CI warrants caution. VAS scores were lower on days 1 and 2 but not day 3 (P=0.093). Subgroup analyses by cognitive assessment instrument, DEX loading dose, and surgical approach showed no significant effect modification (all P≥0.41). In the only trial reporting one-week data, MMSE scores remained higher with DEX on day 7 (MD=0.95, 95% CI: 0.31-1.59), whereas no trial reported POCD incidence beyond day 3. Exploratory publication-bias assessments showed no clear evidence of asymmetry. CONCLUSION: Perioperative intravenous DEX significantly reduces early POCD incidence on postoperative days 1 and 3 and attenuates the early postoperative TNF-α response in elderly patients undergoing abdominal surgery.